An increasing number of people with intellectual disabilities (ID) are at risk of developing age-related disorders such as dementia because of a dramatic increase in life expectancy in this population in the recent years. There is no validated dementia screening instrument for Chinese people with ID. The Dementia Screening Questionnaire for Individuals with Intellectual Disabilities (DSQIID) was reported to be a valid, user-friendly, easy-to-use observer-rated instrument. It was developed in the UK and has good psychometric properties. Validation of a Chinese version of the DSQIID will facilitate its application among the Chinese population.Method
The DSQIID was translated into the Chinese version (DSQIID-CV). By purposive sampling, service users with ID aged 40 years or over were recruited through two large centres serving adults with ID in Hong Kong. Carers who had taken care of the participants continuously for the past 6 months were invited to complete the DSQIID-CV. All participants were examined by qualified psychiatrists to determine the presence or absence of dementia.Results
Two hundred people with ID whose age ranged between 40 and 73 years (mean 51 years, SD = 7.34 years) were recruited to the study. A clinical diagnosis of dementia was established in 13 participants. An overall total score of 22 as a screening cut-off provided the optimum levels of specificity (0.995) and sensitivity (0.923). The DSQIID-CV showed good internal consistency (alpha = 0.945) for all its 53 items, and excellent test-retest reliability (0.978, n = 46) and inter-rater reliability (1.000, n = 47). Exploratory factor analysis resulted in a four-factor solution explaining 45% of the total variance.Conclusions
The DSQIID-CV is shown to have robust psychometric properties. It is the first valid and reliable dementia screening instrument for Chinese adults with ID.